actually thats not the only way to obtain a sponsor...
make a nice portfolio of you car, take pictures of your car inside and the outside. Next make a write up of all the mods you have and everything done to the car. Include you quarter mile times and all important info. Originality is what they look for... so if you drive a everyday rice out bucket of rust

your not gunna get sponsered. send all that info to the company you are intrested in. make it look professional.. also call up the company first to see if they are accepting sponsorship , they will tell you if they are